This invention relates to a wire harness grommet that is mounted on a wire harness passing through a partition wall of a vehicle body or equipment. The grommet is mounted on the partition wall to hold the wire harness in a manner so as to keep the posture of passage of the wire harness straight and orderly, and also to achieve a waterproof effect.
A grommet for a wire harness has a funnel-like shape, and includes a wire-passing tubular portion having a small diameter for passing the wire harness therethrough in pressurized contact with the tubular portion. An annular partition wall-mounting portion having a large diameter is fitted in a through hole in a partition wall of a vehicle body or equipment. The wire harness is passed through the wire-passing tubular portion, and then a filler layer is formed in a hollow portion formed between the outer periphery of the thus-passed wire harness and the funnel-like inner wall surface of the grommet, thereby mounting the grommet on the vehicle body or the like.
However, because the wire harness is subjected to external tension and bending force during use, the filler layer is separated from the inner wall surface (to which the filler layer is bonded) to form a gap, so that the waterproof and dust prevention function achieved by the filler layer may be lost. To overcome this difficulty, there has been proposed a wire harness grommet (disclosed in Japanese Utility Model Unexamined Publication No. 1-66713) in which projections or recesses, serving as means for preventing the separation of a filler layer, are formed on a funnel-like inner wall surface.
In the above construction having the separation prevention means, in order to effectively prevent the separation of the filler layer due to an external force exerted on the wire harness, it is necessary that the projections or recesses have a considerable size. Therefore, when removing the molded grommet from a mold, a considerable mold release resistance is encountered, thus affecting mold release characteristics. Moreover, the projections or recesses may be damaged. Therefore, its configuration is limited to one compatible with the mold release characteristics, and this results in a disadvantage that the separation prevention function is not sufficiently achieved, and hence is not practical.